U.S. Pat. No. 4,302,608 discloses a continuous process for isomerisation of hexafloropropylene oxide (HFPO) to hexafluoroacetone in the presence of an antimony pentafluoride (SbF.sub.5) catalyst.
U.S. Pat. No. 3,213,134 discloses the isomerization of epoxide of perfluoroheptene-1 into perfluoroheptanone-2.
U.S. Pat. No. 3,321,515 teaches that HFPO can be converted into hexafluoroacetone (HFA) by reaction with alumina at 100.degree. C. (yield 47%) or by reaction with AlCl.sub.3.
I. L. Knunyants, V. V. Shokina and E. I. Mysov in Izv. AN SSSR. Ser. Khim. 2725 (1973) CA 80, 95151 (1974) disclose the reaction of HFPO with SbCl.sub.5 at 170.degree. C. to give a mixture of 15% of chloropentafluoroacetone and 80% of HFA.
A. Ya. Zapevalov, I. P. Kolenko, V. S. Plashkin Zh. Org. Khim. 11,1622 (1975), CA 83, 192954 (1975), and A. Ya. Zapevalov, T. I. Filyakova, M. I. Kodess, I. P. Kolenko Zh. Org. Khim. 22 (1), 93-9 (1986), CA 106, 4771 disclose the use of SbF.sub.5 as catalyst for the isomerization of a number of higher epoxides of polyfluoroolefines but all their examples are limited to fluoroolefins without functional groups because of incompatability of SbF.sub.5 with such groups, for example as -C(O)F. See: T. I. Filyakova, R. E. Ilatovskii, A. Ya. Zapevalov Zh. Org. Khim. 27, No10, 2055-60 (1991).
Aluminum chloride has limited use in ring-opening reaction of fluoroepoxides because of extensive formation of by-products. See L. A. Saloutina, A. Ya. Zapevalov, M. I. Kodess, I. P. Kolenko and L. S. German Izv. AN SSSR. Ser. Khim. 1434 (1983), CA 99, 157790 z, 1983.
Use of the present process with its aluminum chlorofluoride Lewis acid catalysts improves upon the processes and catalysts dislosed in the art by allowing for better yields with less by-product formation under generally milder temperature and pressure conditions.